“This is a great first step in our ambitious commitment of making all LEGO bricks using sustainable materials,” Vice President of Environmental Responsibility Tim Brooks said of the move.

Back in 2015, LEGO first announced its goal of using only sustainable raw materials by 2030. While there’s no single accepted definition for “sustainable,” LEGO has a pretty broad definition: “It is to a high degree determined by its source, chemical composition, its use (in a product) and management (at end-of-life), and the impact it can have in both environmental and social areas.”

But the new bricks only address part of the equation — the source. While it’s seen as a positive step that LEGO is further divesting from fossil fuels, there are other problems that arise when a business traffics in plastic. For example, the new plant-based material is technically identical to the old plastic used to make bricks. “Children and parents will not notice any difference in the quality or appearance of the new elements,” Brooks said.

That’s important for LEGO’s bottom line and the customer experience, but not so for the planet. One of the biggest issues with plastic isn’t fossil fuel usage, but the material’s resilience. Widespread plastics production has led to the formation of garbage islands in the Pacific Ocean, literal dead zones for the ocean life that previously occupied that space. Even most bio-based plastics don’t break down naturally.

And LEGO pieces are notoriously resistant to wear and tear. A container ship carrying a shipment of LEGOs tipped near the England coast in 1997, and even twenty years later, perfectly usable pieces are still washing up on shore.

Adrift for 20 years, these LEGO flippers appear perfectly usable.

Unless LEGO can find a way to create biodegradable plastic, it’s hard to see how the company can be truly eco-friendly. Your best bet for saving the planet one brick at a time? Buy used.